Pest Guides

What Weeds Does Tenacity Kill?

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Tenacity is a powerful herbicide that is used primarily for weed control in lawns. Manufactured by Syngenta, it is designed to target a variety of weeds, ensuring your lawn remains lush and healthy. But what weeds does Tenacity kill? In this article, we will delve into the specifics of what Tenacity can do and how you can use it effectively.


Tenacity herbicide is effective in controlling over 46 broadleaf weed and grass species. Some of the most common weeds it kills include Smooth Crabgrass, Southern Crabgrass, Curly Dock, Common Lambsquarter, Lawn Burweed, Tufted Lovegrass, Marestail, Ground Ivy, Yellow Foxtail, Yellow Nutsedge, Unwanted Bentgrass, and Dandelion among others. It is most effective on cool-season turfgrasses.

What is Tenacity?

Tenacity is a selective, systemic herbicide that works to control many different types of weeds in your lawn. The active ingredient in Tenacity is mesotrione, a compound derived from the bottlebrush plant (Callistemon citrinus). Mesotrione inhibits photosynthesis in susceptible plant species, preventing them from creating enough food to grow or maintain their biomass. It is absorbed by plants through the roots, shoots, and leaves and is distributed throughout the plant by both xylem and phloem translocation.

Which Weeds Are Most Affected?

Tenacity is effective in controlling more than 46 broadleaf weed and grass species. Some of the weeds most affected by Tenacity include:

  • Smooth Crabgrass
  • Southern Crabgrass
  • Curly Dock
  • Common Lambsquarter
  • Lawn Burweed
  • Tufted Lovegrass
  • Marestail
  • Ground Ivy
  • Yellow Foxtail
  • Yellow Nutsedge
  • Unwanted Bentgrass
  • Barnyardgrass
  • Black Medic
  • Buckhorn Plantain
  • Buttercup
  • Carpetweed
  • Chickweed Mousear
  • Large Hop Clover
  • White Clover
  • Common Chickweed
  • Creeping Bentgrass
  • Dandelion

Tenacity is most effective on cool-season turfgrasses like Kentucky Bluegrass, Turf Type Tall Fescue, Fine Fescue, and Ryegrass.

How to Apply Tenacity for Maximum Effectiveness

To achieve the best results when using Tenacity, follow these steps:

  1. Timing: Apply Tenacity to a dry lawn in the spring or fall, ensuring the air temperature is between 55°F and 80°F.
  2. Mixing: For smaller applications, mix 0.5 tsp of Tenacity and 1.5 tsp of surfactant with 1 gallon of water, which will cover 1,000 sq ft. A surfactant is recommended to improve weed control and provide better adhesion to the leaf surface of the weeds.
  3. Application: Use a pump sprayer to apply the Tenacity mixture evenly across the target area. If spot treating, use the same mixture ratio.
  4. Reapplication: Some weeds may require a follow-up application after two to three weeks for improved post-emergence weed control.
  5. Mowing: Mow your lawn two days before application and wait two to three days after application before mowing again.
  6. Irrigation: If rainfall hasn’t occurred within 10 days after a pre-emergent application, activate the herbicide with some irrigation.

Remember that Tenacity can damage your lawn if over-applied, so it’s essential to follow the recommended application rates and guidelines.

Precautions and Safety Measures

Using Tenacity requires certain precautions to ensure safety and effectiveness. Always wear protective clothing, avoid contact with eyes and skin, avoid inhalation, and keep children and pets away during application. Store Tenacity out of the reach of children and in a cool, dry place.

In conclusion, Tenacity is a versatile and effective weed killer that targets a wide range of weed species. By understanding what weeds Tenacity kills and how to apply it correctly, you can maintain a healthy, weed-free lawn.

Frequently Asked Questions

Can I use Tenacity on all types of grass?

No, Tenacity is most effective on cool-season turfgrasses like Kentucky Bluegrass, Turf Type Tall Fescue, Fine Fescue, and Ryegrass. It may cause discoloration or damage to other types of grass.

How long does it take for Tenacity to work?

You should start seeing results within a week of application, with weeds turning white as they die. However, some tough weeds may require a second application after two to three weeks for full control.

Can I use Tenacity in my vegetable garden?

No, Tenacity is not recommended for use in vegetable gardens or other edible plants. It is designed specifically for use in lawns to control weed growth.

Is Tenacity safe for pets and children?

Yes, once Tenacity has dried on the lawn, it is safe for pets and children to return. However, during application, it’s recommended to keep children and pets away from the treated area.

Will Tenacity kill my flowers if it gets on them?

Yes, Tenacity is a non-selective herbicide, which means it can potentially harm plants it comes into contact with, including flowers. It’s best to apply it carefully to avoid contact with desirable plants.

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